Tire pressure alarm



Dec. 9, 1952 H. G. BENZ 2,620,762

TIRE PRESSURE ALARM Filed Aug. 13, 1948 Patented Dec. 9, 1952 UNITE Di PAT fur GFZFICE;

My invention relates .to' 'an'iimp'rovenrentfin 1 tire pressure alarm, wherein itisdesired to ro-- vide an apparatus capable of giving an :alarm when the pressure drops below a certain mini mum.

Many tires are ruined dueto the failure of .the 1 driver 'of' a vehicle'to stoppromptlyiwhe'n the air begins to leave the tire.- Iri the case ofa slow leak, the pressure leaves the tire. graduallyxand the tire is often almost flatbefore the driver realizes that the tire pressure is dropping. Many I tires that could'be saved are thus ruined by move: ment of the carafte'r the pressure in th'e tire has dropped below a predetermined minimum.

The object of the present invention lie'sin the provision of a simplemeans capable of sounding 1 an alarm when the pressure in thetiie drops below a predetermined The valarm is in the form of an exploding blank, cartridge mounted upon the wheel.

A feature f the present inventioii'lies in the provision of a support for a blank cartridge mounted upon a .wheel for rctation therewith. The cartridge is Supported adjacent a firiiig. pin capable of exploding the cartridge. A spring urged trigger is pivotally 'supportedriear .the firingpin to actuate the same. The'trigge'r is controlled by action of a Bourdon tube, the interior of which communicates with the interiorof the tire tube. The pressure-within the tire is thus communicated to the interior of the Bourdon tube and the curvature of this tube depends 'upon the contained pressure. When 'thepressure in the tube decreases, the radiusof curvatur of the tube decreases, operating the trigger to explode the cartridge.

.A feature of the present invention lies in the use of a curvedtube closed at its outer end-and connected at its inner end to'the valve'stem of the tire. The tubeis of such a character that the radius of curvature thereof increases in internal pressure in the tube. Accordingly by merely decreasing the pressure Within the. tube a'ndbbnnecting the free end of the. tube to a suitable trigger operating mechanism, a red'ucticn in pressurefin the'tubemaybe employed to-actuate .2 In the drawings forming a part of-my specificationz' Figure '1 is an enlarged elevational view of my tire pressure alarm, partially in section showing the construction thereof Figure 2 is an elevational view of a vehicle wheel showing the manner in which the alarm may be attached thereto.

Figure 3 is an-elevational-view of a detailed portion of my construction. 7

Figure 4 is a sectional view through my alarm, the position of the section beingindicated by the line 6-4 of Fig; 1.

The alarm A includes a cup shaped-body having a generally 'cylindrical flange Ill and a closure wall H at one end-thereof A removable closure disc I2, a 'po'rtion'of which-is illustrated in Figure 1 of the drawings, is'secured to the opposite end of thebodybycap screws l3 or other suitable means.

A'portionof the interior-of'the cup shaped body is filled into provide an internal boss or projection 14 integral'with the cylinder-'wall'lfl andthe end closure member I A pair of spaced ears ['5' project from one portion of this boss 14 and a pivot. pin'lfi' extendsbetween these ears 15.. A lever I! is 'pivotaily supported on the pivot. pin 16. One'en'd of th'e'lever I! is pivotally connected at 19 to a projecting 'ear' 2c-on-the end of a hollow curved tube 2|; Theother-end of the lever IT is provided with "a 'hook'e'clshaped projection 22 .for a 'purposewhich will be later described in detail.

The tube 2| is relatively-wide and 'thin and is curved at approximately the same curvature as the cylindrical wall 1'0 and i's'bf slightly smaller radius. The tube 2| is closed at'itsifree'endis, the cars 29 projecting from "thisr'close'd end. The opposite end of thetube 2| isiinserted' in socket or recess 24 in the boss l t. The tube 'sealed to the-boss !4 so that 'no pressure can escape about the walls of the tube.

The socket 2 4 communicates with 'a radially extending passage .25"'which proje'cts through a radially extending boss 25 on the outer surface of the wall [0. A reduced diameter portion 21 of the boss 25 projects from the boss-and th'epassage 25 extends through this threaded extension. The extension 2'! is threaded into a valve stem 29 connected to the tire tube. The stem 29 may be provided with a branch 39 which contains the conventional valve stem to prevent the escape of pressure from the tube. A valve cap 3| of conventional type may be provided on the stem 30.

A cylindrical aperture 32 extends inwardly into the boss 14 through the cylindrical Wall ID. A

boss 33 is provided on the outer surface of the wall In in axial alignment with the aperture 32. The aperture 32 is designed to accommodate an elongated sleeve 34. A portion of the sleeve 34 near the outer extremity thereof is provided with a reduced diameter opening 35 therethrough. A flange 36 on the outer end of the sleeve 34 provides a means of rotating the sleeve and a portion of the exterior surface of the sleeve near the flange 36 is threaded as indicated at 31 to fit the internal threads of the boss 33. In other words, the elongated sleeve 34 may be threaded into the aperture 32 and held in place by the cooperable threads. 7

A shoulder 39 is provided between the large diameter portion of the sleeve 34 and the small diameter portion 35 thereof. A plug or diaphragm 40 is provided adjacent the shoulder 39 to prevent water and the like from entering through the passageway in the sleeve. A cartridge 4| is enclosed within the sleeve 34, the rim 42 of the cartridge being interposed between the end of the sleeve 34 and the end of the aperture 32 in which the 'sleeve is accommodated.

A pointed firing pin 43 is supported in axial alignment with the cartridge 4| and in position to explode the same. The pin 43 is provided with a peripheral groove 44 extending thereabout, this groove being designed to accommodate the bifurcated end 45 of a flat spring 46. A flat spring 46 is mounted in a groove 41 in the boss M, the spring holding the pin 43 from sliding outwardly from a passage 49 in axial alignment with the aperture 32. The spring 46 holds the firing pin 43 with the pointed end 50 of the firing in in substantial contract with the rim end of the cartridge 4|. The opposite end of the firing pin is held in the path of movement of a striking arm The striking arm or hammer 5| is provided with a hammer end 52 and a pivot which is pivotally mounted upon a pivot 53 to a pair of spaced ears 54 on the boss M. The free end of the hammer 5| is shaped to engage the hook end 22 of the lever I1, this lever acting as a means of holding the hammer from pivotal movement. A spring 55 encircles the pivot 53 and urges the hammer 5| in a counter-clockwise direction as viewed in Figure 1 of the drawings. When the hammer 5| is released by the lever H the spring 55 urges this hammer in a counterclockwise direction to strike against the firing ;pin 43 and to explode the cartridge 4|.

The tube 2| acts in the manner of a Bourdon tube to accomplish the result desired. The tube ;is so constructed that when the interior of the tube is subjected to the pressure normally used within the tire tube, the radius of the tube will be expanded sufficiently to pivot the lever into interlocking relation with the hammer 5|.

However, when the pressure within the tube drops below a predetermined minimum, the radius of curvature of the tube 2| decreases sufilciently to pivot the lever 11 out of engagement with the hammer 5| allowing the hammer to rotate against the firing pin and to explode the, cartridge 4|.

It will be noted that the cartridge 4| may be replaced by removing the sleeve 34 enclosing the cartridge. After the tube has been filled to the proper extent the hammer 5| must be swung into cooperable engagement with the lever II, this lever then acting as a trigger for holding the hammer from operation.

If desired, an aperture 56 may be provided in the rear closure of the housing-to accommodate one of the studs 51 used in holding the wheel 59 supporting the tire 69.

The stud 51 extends through the aperture 56 and a nut 6| is threaded onto the stud to hold the indicator in place and also to hold the wheel in place.

The stem 29 connected to the gauge may, if desired, comprise a flexible tube connecting a branch of the valve stem to the alarm. In any event, the tire pressure within the tire tube is communicated to the interior of the Bourdon tube 2| to actuate the alarm.

As indicated in Figure 4 of the drawings, the pivot 53 extends through the front closure plate l2. The projecting end 62 of the pivot 53 is squared or flattened to extend into the socket end 63 of a removable key 64. The key 64 may be used to rotate the pivot 53 and the hammer 5| which rotates therewith. The hammer can be reset by use of the key 64 when pressure is provided within the tire.

In accordance with the patent statutes, I have described the principles of construction and operation of my tire pressure alarm, and while I have endeavored to set forth the best embodiment thereof, I desire to have it understood that obvious changes may be made within the scope of the following claim. without departing from the spirit of my invention.

I claim: I

A tire pressure alarm including a pressure actuated member, means connecting said pressure actuated member to a tire to communicate tire pressure thereto, a trigger pivotally. supported adjacent said pressure actuated member and normally urged in one direction, said pressure actuating means controlling the actuation of saidtrigger to release said trigger upon a drop in tire pressure, a cartridge supported adjacent to said trigger, a firing pin supported in the path of movement of said trigger and engageable with the cartridge to actuate the same, and means removably secured to said trigger for rotating the trigger in a direction to reset the same.

HERBERT GEORGE BENZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 583,543 Nelson .4 June l, 1897 1,156,862 Sibley Oct. 12, 1915 1,281,274 Berry Oct. 15, 1918 1,800,801 Marklund Apr. 14, 1931 2,268,783 Tate Jan. 6, 1942 

